Casey Bralla on 29 Jun 2009 18:07:35 -0700

[Date Prev] [Date Next] [Thread Prev] [Thread Next] [Date Index] [Thread Index]

[PLUG] Find Open Ports

My employer is very aggressive in closing off ports.  This makes it hard for me 
to access my home network from work.  Luckily, port 23 is open so I can ssh 
in, and of course, port 80 is left alone.

However, I've got several special web pages that run on computers behind my 
firewall.  I access them through port forwarding to non-standard ports (such as 
81 & 82).

Unfortunately, since my employer blocks these ports, I can't use them.   I do 
have unlimited discretion, however, in assigning my programs to whatever port 
I desire.

So....  if I knew which ports were NOT blocked, I could use those.

BUT...  How do I check to see if what ports are available?

So far, I've been able to come up with 2 ideas:  1) scan every port, and 2) 
try ports manually one at a time.

I could run a portscan on my portable, but that would undoubtedly raise all 
kinds of alarms.  Also, I'd have to be sure I was connecting to something that 
had those ports active.

Does anybody have any suggestions on how to test to see if a series of ports 
is not filtered, or have a suggestion of ports that I could test manually 
through trial and error?

Casey Bralla
Chief Nerd in Residence
The NerdWorld Organisation
Philadelphia Linux Users Group         --
Announcements -
General Discussion  --